1. Field of the Invention
The present invention is generally directed to a stair system, and more particularly to modular treads and risers of a stair system.
2. Description of Related Art
Generally, stair systems having nose moldings have been constructed in a similar manner using the same basic methods. For example, most stair systems employ a plurality of stringers having tread sides cut out, on which are secured tread sub flooring that span between the stringers. The stringers also have riser sides cut out, on which are secured riser sub floorings that also span between the stringers. Depending on the finishing materials for the stair system, a tread and riser may be mounted to the tread sub flooring or carpeting, with or without padding, may be affixed to the tread sub flooring and riser sub flooring. Where carpeting is used, the tread sub flooring may provide an overhang to allow the carpet to be affixed to the underside of the overhang, thereby hiding the means of fastening the carpet to the tread sub flooring. Sub flooring is normally secured using nails, screws, and/or adhesives
Because most stair systems are normally built from the top down, in the case of steps having a wood finish, the top most tread is attached using adhesive and a stair nose is attached to the end of the tread to overlap a portion of the tread and to cover the remainder of the tread sub flooring. Generally the stair nose extends beyond the tread sub flooring a sufficient distance to allow a riser to be disposed beneath the stair nose.
The first step below the top step is assembled by placing a riser underneath the stair nose and affixing it to the riser sub flooring using either fasteners or adhesive. The next tread must be cut to have a square edge, as it must abut the riser. Then the stair nose is attached to the end of the tread to overlap a portion of the tread and to cover the remainder of the tread sub flooring as discussed above. This process is repeated for each successive step.
In an alternative stair system, the stair nose may be affixed to the tread by using a tongue and groove relationship. The tread and risers are affixed to the tread sub flooring and riser sub flooring using fasteners or adhesive as described above. In all of the above cases, it is important that expansion of the wood be accounted for in the assembly of the stairs. As such, sufficient gaps must be provided between pieces of wood to allow the individual pieces to expand.
The first system permits the tread and risers to be free-floating, allow them to contract and expand with changes in temperature and humidity. However, they are unattractive in that the stair nose is higher than the tread because of the overlapping arrangement. The second system does allow the tread and stair nose to be coplanar, but because they are joined by the tongue and groove, the system does not allow the tread and risers to be free-floating.
U.S. Pat. No. 6,115,975 proposes a solution to providing a nose stair that is coplanar with the tread, but still allows the tread and riser to be free floating. The stair system provides a stair nose connected by a tongue and groove arrangement to a tread. A back molding is affixed to the tread and includes a groove to receive a riser therein. A corresponding groove is formed in the stair nose such that the riser is held between the stair nose and the back molding. In this manner, the riser can be allowed to expand and contract with the temperature and humidity, thereby providing treads and risers that are free floating.
However, U.S. Pat. No. 6,115,975 is a complicated system that requires many additional components. As a result the assembly process is unnecessarily complicated.